(a) Field of the Invention
The present invention relates to a method of fabricating a silicon rubber-based mold and, more particularly, to a method of fabricating a silicon rubber-based mold which contains minimum amount of silicon rubber and improves molding characteristics of the product to be formed.
(b) Description of the Related Art
Generally, rim molds or vacuum casting molds that are mainly used for the casting purpose involve high production cost and retarded production time because they should be fabricated separately in accordance with the shape of the required products. Therefore, in case various kinds of products should be formed in a small scale, the molds based on silicon rubber or epoxy resin have been extensively used.
FIGS. 3A to 3D illustrate the processing steps of fabricating a silicon rubber-based mold according to a prior art. As shown in FIG. 3A, a jig 112, and a master model 114 of products to be formed are first made. Thereafter, as shown in FIG. 3B, the master model 114 is mounted onto the jig 112. As shown in FIG. 3C, the master model 114 mounted on the jig 112 is inserted within a casting enclosure, and then, silicon rubber is injected onto the master model 114 to thereby form a lower half mold 116. The lower half mold 116 is overturned, and the jig 112 is separated from the master model 114. Thereafter, silicon rubber is again injected onto the master model 114 to thereby form an upper half mold 118. Finally, the master model 114 is removed from its place while leaving out an empty space for forming the required products there.
Silicon rubber used in such a process is flexible, and coefficient of thermal expansion thereof is up to 0.01. Therefore, considering that the product formation using a mold is performed under the high pressure of 1-1.5 MPa, the above structured mold that is entirely based on silicon rubber is liable to suffer serious transformation due to its high thermal expansion, and causes poor dimensional precision of the resulting products.
On the other hand, the mold based on epoxy resin involves complicated processing steps due to physical properties of the epoxy resin. Furthermore, since the required flexibility is absent in the epoxy resin-based mold, serious transformation of the product is generated at mold release.